Impedance control is a technique for controlling positions and forces. Impedance control for machines is to control their positions and forces to control mechanical impedance (inertia, an attenuation coefficient, and stiffness) in response to an external force applied to a control target to achieve intended motions. Patent Literature 1 describes a parameter adjustment apparatus that adjusts parameters used in impedance control based on information provided from a force sensor mounted on an end effector of a robot.